Le Bristol Brabazon : 1949
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Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 10:04
Phase 8 : L'équipage des tests.
[Vous devez être inscrit et connecté pour voir ce lien]The Flight Test crew
The ten man flight test crew were keen young men, some of whom had flown during the war and others who were factory trained or engineers from university. They were to put their combined talent talents to good use.
One of them, Ken FitzGerald, 28 and married to Anne joined Bristol Aeroplane Company in 1937 as an electrician and was the only Bristolian in the crew.
The Bristol Evening Post had written about the 1,000 test dials that the crew would be monitoring. For these they devised many ingenious camera systems to record the findings. This was pre-computer technology and all the data would need to be manually collated and checked.
The crew now had many months of intensive flight-testing, all the systems were new and their feedback to the design teams was crucial. They tested the new technology to its limits, Bill Pegg being in his element, the RAF, many years before had noted his outstanding ability as a natural aviator but had failed to keep him. Now as BAC's Chief test pilot, even a hydraulic pipe failure just became a normal landing and a good test of the reversing propellers, even with flaps still up. Filton's long runway was also an asset. That was on January 16th 1950.
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Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 10:06
Brabazon Flight test crew. The crew pose for a publicity picture. This was a new phenomenum for test crews in the late 40's. They had suddenly become national hero's and would be taking the hopes of the nation with them when flying the great bird that was the Brabazon. The newspapers of the day latched onto something positive after so much gloom in the aftermath of world war. The crew: Back row: (L to R) J M Cochrane (Flight test observer, aircraft); M W West (Flight test observer, aircraft); A Cowan (Flight engineer, aircraft); John Sizer (Flight test observer, aircraft); Ken FitzGerald (aircraft electrical engineer). Front row: L D Atkinson (chief flight engineer, engines); W Gibb (co-pilot); A J Pegg (pilot); M J Peniston (chief flight test observer, aircraft); H J Hayman (flight engineer, engines).
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Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 10:14
Dernière étape : La fin et la destruction
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The Final failure and destruction
What went wrong? Well nothing; the aircraft was built, flown and proved itself worthy. What had happened was that the world economics following a World War moved on too fast no longer were nations helping one another but instead fiercely competing for the markets to pay for the war.
America had done well, being given the jet engine technology and the wartime right to produce transport aircraft. Now in the war's aftermath they had masses of redundant aircraft with a seemingly endless supply of spares. American salesmen exploited this globally and gained markets. These markets would easily convert when the likes of Boeing and McDonnell Douglas came along with their new post war jet airliners, the 707 and the DC8.
The Brabazon nevertheless, had shown the way, it had pioneered fully powered flying controls, it had laid the standards for air conditioning and cabin pressurisation. The decision to use gas turbines came too late, but even with these, the marketing was wrong. The Americans realised that people wanted to travel; they wanted to come to Europe to see for themselves the devastation and the places where loved ones were buried. The Brabazon was marketed for rich passengers to fly in luxury and the lead that aircraft manufacturers in the UK could have had was gone. It nearly regained it with the Comet but accidents put this aircraft out of the picture. The Americans never looked back.
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Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 10:33
Reprenons sur Wikipedia... [Vous devez être inscrit et connecté pour voir ce lien]
The Bristol Type 167 Brabazon was a large [Vous devez être inscrit et connecté pour voir ce lien], designed by the [Vous devez être inscrit et connecté pour voir ce lien] to fly [Vous devez être inscrit et connecté pour voir ce lien] routes from the [Vous devez être inscrit et connecté pour voir ce lien] to the [Vous devez être inscrit et connecté pour voir ce lien]. The prototype was delivered in 1949, only to prove a commercial failure when airlines felt the plane was too large and expensive to be useful. Despite its size, comparable to a [Vous devez être inscrit et connecté pour voir ce lien], it was designed to carry only 100 passengers, albeit in roomy conditions not generally found on modern aircraft. In the end, only a single prototype was flown; it was broken up in 1953 for scrap, along with an uncompleted second [Vous devez être inscrit et connecté pour voir ce lien].
Design and development
Background
In 1943, a British government committee met under the leadership of [Vous devez être inscrit et connecté pour voir ce lien] to investigate the needs of the British civil airliner market.
The [Vous devez être inscrit et connecté pour voir ce lien] delivered a report, known as the "Brabazon Report", calling for the construction of four of five designs they had studied. Type I was a large transatlantic airliner, Type III a smaller airliner for the [Vous devez être inscrit et connecté pour voir ce lien] air routes, and Type IV a jet powered 500 mph (800 km/h) airliner. The Type I and IV were considered to be very important to the industry, notably the jet powered Type IV which would give the UK a commanding lead in jet transports.
Bristol had already studied a large [Vous devez être inscrit et connecté pour voir ce lien] design starting as early as 1937, but nothing had come of this. In 1942 the [Vous devez être inscrit et connecté pour voir ce lien] published a tender for a new super-[Vous devez être inscrit et connecté pour voir ce lien] design, and Bristol dusted off their original work and updated it for their newer and much more powerful [Vous devez être inscrit et connecté pour voir ce lien] engines. This led to a design with a range of 5,000 mi (8,000 km), 225 ft (69 m) wing span, eight engines buried in the wings driving four [Vous devez être inscrit et connecté pour voir ce lien] propeller installations, and enough fuel for transatlantic range. This "100 ton bomber" and designs from the other major manufacturers were in many ways the British analogues to the American [Vous devez être inscrit et connecté pour voir ce lien]. However in expectation of long development times, the Air Ministry later changed their mind and decided to continue development of the [Vous devez être inscrit et connecté pour voir ce lien], (leading to the [Vous devez être inscrit et connecté pour voir ce lien]) instead.
Bristol 167
A year later, the Brabazon Report was published and Bristol was able to respond with a slightly modified version of their bomber to fill the needs for the Type I requirement. Their earlier work was the sort of performance the Brabazon committee was looking for, and they were given a contract for two prototype aircraft. After further work on the design, a final concept was published in November 1944. It was for a 177 ft (54 m) fuselage with 230 ft (70.1 m) wingspan (35 ft/11 m greater than a Boeing 747) powered by eight [Vous devez être inscrit et connecté pour voir ce lien] 18-cylinder [Vous devez être inscrit et connecté pour voir ce lien] nested in pairs in the wing. These drove eight paired [Vous devez être inscrit et connecté pour voir ce lien] on four forward-facing nacelles.
The Brabazon Report was backward-thinking in one aspect, however. When considering the people who would fly in the aircraft they designed, they thought in the context of wealthy people or those on governmental work as being the only ones able to afford air travel at that point. The idea that a larger aircraft would make flying less expensive, and thereby open the market to a wider clientele, never appears to have occurred to them.[[Vous devez être inscrit et connecté pour voir ce lien]] Instead they assumed that the wealthy flying the plane would consider a long trip by air to be uncomfortable, and they designed the Type I for luxury, demanding 200 ft³ (6 m³) of room for every passenger, and 270 ft³ (8 m³) for luxury. This is similar to the interior room of a small car.
To meet these requirements the Type 167 specified a huge 25 ft (8 m)-diameter fuselage, which is about 5 ft (1.5 m) greater than a 747, with full-length upper and lower decks. This enclosed sleeping berths for 80 passengers, a dining room, 37-seat cinema, promenade and bar; or day seats for 150 people. The Committee recommended a narrower fuselage designed for 50 passengers. [Vous devez être inscrit et connecté pour voir ce lien] agreed, but preferred a design for only 25 passengers. An agreement with the airline eventually led to an interior layout housing a forward area with six compartments, each for six passengers and a seventh for just three; a mid-section above the wing - the wing was 6 feet deep at that point - with 38 seats arranged around tables in groups of four with a [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien]; and a rear area with 23 seats in an aft-facing cinema with a cocktail bar and lounge. Like the [Vous devez être inscrit et connecté pour voir ce lien], the Brabazon concept was a fusion of pre-war and post-war[[Vous devez être inscrit et connecté pour voir ce lien]] thinking, using highly advanced design and engineering to build an aircraft that was no longer required in the post-war world.
A tremendous effort was put into saving weight. The Type 167 used a number of non-standard gauges of skinning in order to tailor every panel to the strength required, thereby saving several tons of metal. The large span and mounting of the engines close inboard, together with structural weight economies, demanded some new measure to prevent bending of wing surfaces in turbulence. A system of gust alleviation was developed for the Brabazon, using servos triggered from a probe in the aircraft's nose. Hydraulic power units were also designed to operate the giant control surfaces. The Brabazon was the first aircraft with 100% powered flying controls, the first with electric engine controls, and the first with high-pressure hydraulics.
Building the aircraft was a challenge. Bristol's existing factory in [Vous devez être inscrit et connecté pour voir ce lien] was too small to handle what was one of the largest aircraft in the world, and the 2,000 ft (610 m) runway was too short to launch it. Construction of the first prototype's fuselage started in October 1945 in an existing [Vous devez être inscrit et connecté pour voir ce lien] while a gigantic hall for final assembly was built, whose designer, [Vous devez être inscrit et connecté pour voir ce lien], was awarded the [Vous devez être inscrit et connecté pour voir ce lien] for the work. The runway was lengthened to 8,000 ft (2,440 m), which required moving elsewhere the inhabitants of the village of [Vous devez être inscrit et connecté pour voir ce lien].
Some design and construction work was shared out to other British companies such as [Vous devez être inscrit et connecté pour voir ce lien].
Mark II
In 1946 it was decided to make the second prototype based on the [Vous devez être inscrit et connecté pour voir ce lien] engines - eight paired turboprops driving 4-bladed screws through a common gearbox.. This would increase cruising speed from 260 to 330 mph (420–530 km/h) and ceiling while reducing the empty weight by about 10,000 lb (4,540 kg). This Brabazon Mark II, would be able to cross the [Vous devez être inscrit et connecté pour voir ce lien] (London-New York) in a reduced time of 12 hours.
Although the Proteus was slimmer than the Centaurus, the wing thickness was not to be reduced in the Mark II but the leading edge would be extended around the engines.
Changes to the wheel arrangement planned for the Mark II would have allowed it to use most runways on both the North Altantic and Empire routes.
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Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 10:36
Specifications (Mark I)
General characteristics
- Crew: 6-12
- Capacity: 100 passengers
- Length: 177 ft (54.0 m)
- [Vous devez être inscrit et connecté pour voir ce lien]: 230 ft (70 m)
- Height: 50 ft (15 m)
- Wing area: 5,317 ft² (494.0 m²)
- [Vous devez être inscrit et connecté pour voir ce lien]: Root T.P.4 (mod) Tip T.P.5
- Empty weight: 145,100 lb (65,820 kg)
- [Vous devez être inscrit et connecté pour voir ce lien]: 290,000 lb (130,000 kg)
- Powerplant: 8× [Vous devez être inscrit et connecté pour voir ce lien], 2,650 hp (1,860 kW) each
- Propellers: paired contra-rotating 3-bladed Rotol
- Propeller diameter: 16 ft ()
Fuel capacity 13,650 Imp gal
Performance[Vous devez être inscrit et connecté pour voir ce lien]: 300 mph (260 kn, 480 km/h) at 25,000 ft [Vous devez être inscrit et connecté pour voir ce lien]: 250 mph (220 kn, 400 km/h) at 25,000 ft Range: 5,500 mi (4,800 nmi, 8,900 km) at 250 mph and 25,000 ft Service ceiling 25,000 ft (7,600 m) at full weight [Vous devez être inscrit et connecté pour voir ce lien]: 750 ft/min () at sea level Max [Vous devez être inscrit et connecté pour voir ce lien]: 54 lb/ft² (270 kg/m²) Minimum [Vous devez être inscrit et connecté pour voir ce lien]: 0.073 hp/lb (120 W/kg)
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Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 10:38
Testing
The Mk.I aircraft, registration G-AGPW, rolled out for engine runs in December 1948, and flew for the first time, over [Vous devez être inscrit et connecté pour voir ce lien] for 25 minutes, on 4 September 1949 captained by Bristol Chief Test Pilot Bill Pegg. It flew to about 3,000 ft (910 m) at 160 mph (257 km/h) and landed at 115 mph (185 km/h), throttling back at 50 ft (15 m). Four days later, it was presented at the [Vous devez être inscrit et connecté pour voir ce lien] before starting testing in earnest. It was demonstrated at the 1950 Farborough Airshow with a take-off, clean configuration fly-past and a landing. In June 1950, she visited London's [Vous devez être inscrit et connecté pour voir ce lien], making a number of successful takeoffs and landings, and was demonstrated at the 1951 [Vous devez être inscrit et connecté pour voir ce lien]. By this point, BOAC had lost any interest in the design, if it ever really had any, and although some interest was shown by [Vous devez être inscrit et connecté pour voir ce lien] on flying the prototype itself, various problems that would be expected of a prototype meant it never received an airworthiness certificate
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Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 10:40
Cancellation
By 1952, about £3.4m had been spent on development (£53.4m year in year-2000 pounds) and it showed no signs of being purchased by any airline. In March, the British government announced that work on the second prototype had been postponed. The cancellation of the project was announced by the Minister for Supply (Duncan Sandys) on 17 July 1953 in the Commons saying that it had given all the useful technical knowledge it could but with no interest from civil or the military they had no justification for continuing to spend money on it. About 6 million pounds had been spent and a further 2 would be required for the completion of the Mark II. The buildings and runway had cost a further £6 million. In October 1953, after 164 flights totalling 382 hours flying time, the first prototype was broken up, along with the uncompleted Mk.II prototype. All that remains are a few parts at the [Vous devez être inscrit et connecté pour voir ce lien] and Scotland's [Vous devez être inscrit et connecté pour voir ce lien].
Although considered a failure and a [Vous devez être inscrit et connecté pour voir ce lien], the record of the Brabazon is not entirely unfavourable. At least half of the large sums spent on the project were put into infrastructure, including the large hangars and runway at Filton. This meant that Bristol was now in an excellent position to continue production of other designs and the hall was used for building the Britannia aircraft. In addition, many of the techniques developed as a part of the Brabazon project were applicable to any aircraft, not just airliners.
Bristol had also won the contract for the "unimportant" Type III aircraft, which they delivered as the [Vous devez être inscrit et connecté pour voir ce lien]. Using all of the advancements of the Brabazon meant the Britannia had the best [Vous devez être inscrit et connecté pour voir ce lien] of any aircraft up to that point, and it kept that record for a number of years. Although the Britannia was delayed after problems with the Type IV, the [Vous devez être inscrit et connecté pour voir ce lien], it went on to be a workhorse for many airlines into the 1970s. The Britannia is still considered by many to be the ultimate propeller driven airliner.
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